Key to species of the Strumigenys mnemosyne group based on worker caste

(Adapted from the Southeast Asia Strumigenys key of Bolton [3] branching from couplet 84 and ending at couplet 87)

1. Cephalic dorsum behind clypeus uniformly finely and densely reticulate-punctate (Fig 6A, D); pronotum smooth and shining, contrasting strongly with the head (Fig 6B)...... Strumigenys mazu

• Cephalic dorsum behind clypeus and pronotum smooth and shining, the two not contrasting (Fig 2A–I; Fig 3A–C; Fig 4A–C; Fig 8A–C; Fig 9A–C)...... 2

2. Leading edge of antennal scape without straight standing setae of any form (Fig 2D; Fig 4A; Fig 8A)...... 3

• Leading edge of antennal scape with 2–3 straight standing setae that freely project anterodorsally Fig 2A, G; Fig 3A, D; Fig 9C).... 5

3. Dorsolateral margin of mesosoma marginated (Fig 8B–C, E–F); in lateral view, mesosomal dorsum flat (Fig 8B, E)… Strumigenys rimdahli sp. nov.

• Dorsolateral margin of mesosoma curved (Fig 2E; Fig 4B); in lateral view, mesosomal dorsum convex (Fig 2E; Fig 4B); … 4

4. In full-face view, head with four freely projecting setae that extend beyond the lateral cephalic margin (Fig 2D); HW 0.30… Strumigenys mnemosyne

• In full-face view, head without freely projecting setae that extend beyond the lateral cephalic margin (Fig 4A, F); HW 0.34–0.39 ……… Strumigenys marmorata sp. nov

5. Distinctly larger species with a narrow head and longer scape, HL 0.48–0.52; CI 70–74; SI 59–63 …. 6

• Smaller species with relatively broader head and shorter scape; HL 0.40–0.42; CI 80–81; SI 50–53 … 7

6. Dorsum of clypeus in profile with short fine erect setae present (Fig 2H). In full-face view, lateral margin of clypeus with 1–2 straight setae that project out beyond the margin (Fig 2G). Basigastral costulae present (Fig 2I)..... Strumigenys taphra

• Dorsum of clypeus in profile without short fine erect setae, appressed setae only (Fig 3B). In full-face view, lateral margin of clypeus without 1-2 straight setae that project beyond the margin (Fig 3A, D). Basigastral costulae absent (Fig 3C, F) …. Strumigenys liui sp. nov.

7. Posterior margin of head on each side of the median concavity with a translucent blister-like area that occupies about half the width of the posterior margin of the posterior lobes (Fig 2A) …….. Strumigenys daspleta

• Posterior margin of head on each side of the median concavity with a narrow marginal carina across the whole width of the posterior margin of the posterior lobes (Fig 9C)...... Strumigenys runa